WLAN is a flexible data communication system, usually deployed in so-called hotspots, such as airports and hotels, to provide data transmission services. People can use wireless terminals, such as mobile phones or laptops, via wireless access, to access the network resources in a WLAN, and the resources on Internet connected with the WLAN.
WWAN is a communication system which covers more broader areas, and is deployed to provide voice and data services. For example, Global System for Mobile Communication (GSM), General Packet Radio Service (GPRS), Code Division Multiple Access (CDMA) and Third-Generation Mobile Communication (3G) systems all fall in the category of WWAN.
Generally, WWAN provides voice service, whereas WLAN provides data service. However, with the development of communication technologies, the requirement for low-speed data services has emerged in WWAN, and IP-based voice service (VOIP) has also become a new spotlight in WLAN.
FIG. 1 shows the typical use of conventional WLAN and WWAN mobile combo products, wherein the WWAN service area may or may not overlap with the WLAN service area (as shown in FIG. 1). In the process where a mobile user out of WLAN service area is making a voice call via WWAN service, said user may enter into a WLAN service area due to the change of his position. If both parties are in the range of WLAN and they still employ the service of WWAN, their communication cost would not be reduced; but if the WWAN service is switched to the WLAN service, not only the WWAN radio resource but also the cost for end users can be saved greatly. Moreover, richer services, such as video call, can be provided. If one party of the communication is leaving the WLAN service area, it should handover the WLAN service back to WWAN service to ensure that the communication can go on.
As mentioned above, a communication method and apparatus is needed to handover between WWAN and WWLN, so as to effectively reduce the cost for users and save network resources of WWAN.